Electromagnetic step-by-step switch with magnetic brake



Feb. 19 1924.

H. W. GOFF ELECTROMAGNETIC STEPBYSTEP SWITCH WITH MAGNETIC BRAKE Filed Aug. 7, 1920 n W may M n0 eG w Patented Feb. 19,1924.

UNITED STATES PATENT orncs.

HAROLD W. G'OFF, OF NEW YORK, N. Y., ASSI GNOB TO WESTERN ELECTRIC COMPANY,

INCORPORATED, OF YORK, N. Y., A CORPORATION OF NEW YORK. ELECTROMAGNETIC STEP-BY-STEP SWITCH WITH MAGNETIC BRAKE.

Application ma au ust 7, 1920. Serial No. 402,002.,

To all whom it may concern:

Be it known that I, Harrow W. Gone, a citizen of the United States, residing at New York, in the county of New'York and State of New York, have invented certain new and useful Improvements in Electromagnetic Step-by-Step Switches with Magnetic Brakes, of which the following is a full, clear, concise, and exact description.

This invention'relates to electromagnetic devices and more particularly to devices of that, kind adapted for electrical switching purposes. The specific embodiment of the invention as hereinafter described, comprises a movable contact rotary switch provided with a magnetic brake for stopping the moving element.

In step-by-step switches of the type can ploying a pluralityof stationary contacts and a movable contact brush cooperating therewith, it is essential that a positive means be employed for stopping the movable brush member in order to prevent over-- throw, that is to prevent the movable brush movin ast the stationa contact on which is intended to be stopped at the end of each step.

It necessarily follows that abrupt stopping of the movable member results in noisy operation as Well as considerable wear and tear on the switch mechanism and it is as cordingly the object of the present invention to provide a stopping means for electro magnetic switches which does not act to abruptly stop the rapidly moving member, but rather to bring it to a more gradual stop thereby reducing the noise and wear to a considerable degree.

A feature of this invention resides in the application of a magnetic brake to an elec-- tromagnetie step-by-step switch, so arrangd as to graduall retard the moving contact member near t e end of each step except the last step of any series of steps. A further feature residesin the application of a positive stop which goes into action after the magnetic brake has been applied so that the force of impilct between the moving member and the positive stop is ver small.

One specific embodiment of t is invention is illustrated in the accompanying drawin in which Fig. 1, is a side elevation partial y in section, showin a step-by-step switch Fig. 2, is an elevation of the left-hand end Washers it), also of Fi 1; and Fig. 3, is an elevation of the rightand end of Fig. 1.

On the supporting late 1, there is shown mounted a semi-circu contacts 2, comprising six rows and cooperating therewith are a set of rotatable brushes 3, which are insuiatively mounted and rotatable with shaft 4. Also mounted on plate 1, is an electromagnet 5, having a core 6 of nonmagnetic materiai which is rovided with a iongitndinal aperture in w ich shaft journaled;

Eleetromagnet 5 is provided, at its lefthand end, (Fig. 4); with a poie piece 7, which is secured to the core 6. Supporting plate 1 being of magnetic materiai, forms the opposite pole piece mature 8 is pivetaiiy mounted on pin 2 which extends between pole piece 7' and plate 1. Pin 9 is made of nonmagnetic material. made of nonmagnetic ma terial, are mounted on pin 3 and serve as separators between the poie pieces and the mounting legs of armatnres, thereby pre venting e magnetic flux from having a path when the armature is in its reieased position, shown.

Ratchet wheei ii is secnreiy mounted on the shaft at the right-hand end of the electromagnet and a stepping pawl 18 attached to the armature is arranged to drive the ratchet wheel. 11 together with shaft 4, brushes 3 and stopping ratchet 12. Ratchet wheel 11 is of non-magnetic material and sto ping ratchet 12 is of magnetic material. topping pawl 13 carried by armature 8 arranged to swing into engagement with stopping ratchet 12 at the instant the armature reaches its farthest released which time, brushes 3 are proper y centered on one of the sets of stationary contacts of the terminal bank 2. On each forward stroke of the armature, pawl 13 swings out of the path of the teeth of ratchet 12 and on the release stroke of the armature, ratchet 12 is rotated sufficiently to move the end of one tooth past the point of pawl13 before the }latter again swings into the path of the teet Contact springs 14 and '15 are arra d to be operated b pawl 18 to make and rank the circuit 0 electromagnet 5. On each downward stroke of armature 8, pawl 18,

.riding on the back of one of the teeth on ar bank of stationary osition, at

for eiectromagnet 5. Ar-

y it pawl 18 and rotating thereby ratc ratchet 11, holds contact springs 14 and 15 together by virtue of its contact with insulator 16 attached to spring 15, until it dro into the recess of the next succeeding too whereupon contact springs 14 and 1 5 separate thu breaking the circult of electromagnet 5. Armature 8 is returned to its released positionby spring 17 carrying with et 11. The relation between ratchet 11 and. pawl 18, as will be seen in Fig. 3, 18 such that as the pawl 18 travels upwardly with the armature, it is moved outwardly toward the contact springs. At a point approachmgthe end of the release stroke, the contact springs 14 and 15 are forced together thus causing the electromagnet to be energized at that instant whereupon stopping ratchet 12 is moved by magnetic attraction into frictional engagement with ole piece 7 thereby providing a retarding orce which tends to stop further rotation of the shaft and actually slows the shaft down-to such a speed that when pawl 13 engages the stopping ratchet 12, there is practically no accompanying noise.

On the last step of any series, the current is cut-off so that the ma etic brake cannot act, and pawl 13 abru t y stops ratchet 12. There is therefore, on y one stoppin click of any consequence emitted for eac complete operation of the switch.

In Fig. 3 a diagrammatic representationof an appropriate circuit for this switch is shown. Electromagnet 5 is illustrated therein in dotted lines. For each set of stationary contact terminals in the bank, there is provided a relay 19 with an armature 20 which, when operated, puts ground on its respective terminal completing the circuit for electromagnet 5 when contact springs 14 and 15 are closed.

What is claimed is:

1. In combination, an electromagnetic switch, comprising a bank of stationary'contact members, rotatably movable contact member cooperating therewith, an electromagnetic brake operable to retard the rotation of said movable contact members, and a device operable to positively prevent overthrow of said movable contact members when said cooperation with the stationary contact members is effected.

2. In combination, an electromagnetic step-by-step switch, comprising a stationary contact member, a rotary contact member cooperating with said stationary contact member, a shaft for rotating said rotary contact member, step-by-step means for rotating said shaft, a ratchet wheel on said shaft, 'a'

pawl operable to engage and stop said ratchet wheel together with said shaft and rotary contact member at the end of each step and electromagnetic means for frictionally enga ing said ratchet wheel prior to the end 0% each ste thereb retardin the motion of said ratciiet whee shaft an rotary contact member.

3. An electromagnetic step-by-step switch comprising a stationary contact member, an electromagnet, a shaft extending through the core of said electromagnet, a contact brush mounted on said shaft and rotatable therewith, a stepping ratchet wheel on said shaft, an armature for said electroma et, a ste ping pawl for said stepping ratc et operab c said armature, a stopping ratchet on said shaft situated within the magnetic field of said electroma et adapted upon energization of said e ectromagnet to frictionally engage a stationary part of aid electromagnet, a stopping member operable by said armature to engage said stopping ratchet at the end of each step and prevent overthrow thereof, a source of current for said electromagnet, and means operable to apply said current to said electromagnet prior to the completion of a release movement of said armature.

4. An electromagnetic step-by-step switch, comprising an electromagnet, a core of non magnetic material for said electromagnet, a supporting plate of magnetic material forming a part of the magnetic circuit of said electromagnet and situated at one end thereof, a pole piece for the other end of said electromagnet, a rotatable shaft of magnetic material extending through said supportin plate, core and pole piece, an armature or said electromagnet; a stepping ratchet mounted on said shaft and rotatable therewith, a stepping pawl carried by said armature, operable to move said stepping ratchet one step upon each release movement of said armature, a stopping ratchet mounted on said shaft in close propinquity to said pole piece and adapted to be drawn into frictional enga ement therewith upon energization of sai electromagnet, a stationary contact member and a contact brush mounted on said shaft and rotatable therewith, ada ted to engage said stationary contact mem r.

In witness whereof, I hereunto subscribe my name this 28th day of July A. D., 1920.

. HAROLD w. core. 

